Mechanical anti-disturbance device

ABSTRACT

This invention relates to a mechanical anti-disturbance device for preventing the movement of a munition after it has been emplaced. The device uses a movable pendulous mass as a triggering means for releasing a restraining means which is fixedly holding a spring biased firing pin to a housing means when the device is in an armed state.

e 1 h b ilmie Siales afiei 1 1 1 adfield 1 1 May 1, 1973 54 MECHANICAL ANTLDIS 3,030,886 4/1962 Junghans et al. ..102/7q DEVICE 2,850,978 9/l958 Franklin 3,205,817 9/1965 Madlener et al. [75] inventor: Harry J. Hadfield, Califon, NJ. 3,603,258 9/1971 Green ..102 79 [73] Assignee: The United States of America as represented by the Secretary of the Primary Examiner-Samuel W. Engle Army Att0rneyHan'y M. Saragovitz et al.

221 Filed; July 12, 1971 [21] Appl. No.: 161,585 [57] ABSTRACT This invention relates to a mechanical anti- [52] 11.8. CI. ..102/70 S, 102/8, 102/ 16 i r n device f r preventing the movement of a [51] int. Cl. ..F42c 7/02 munition after it has been emplaced. The device use; [58] Field of Search ..l02/8, 70, 78, 76, a movable pendulous mass as a triggering means for 102/79, 16 releasing a restraining means which is fixedly holding a spring biased firing pin to a housing means when the [5 6] References Cited 3 device is in an armed state,

UNITED STATES PATENTS 1 Claim, 4 Drawing Figures 2,436,837 3/1948 Traylor ..l02/70 Patented May 1, 1973 3,730,100

2 Sheets-Sheet 1 INVENTOR.

HARRY J. HADFIELD Patented May 1, 1973 3330mm 2 Sheets-Sheet 2 INVENTOR.

HARRY J. HADFIELD MECHANICAL ANTI-DISTURBANCE DEVICE The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION Various means have been used in anti-disturbance devices to activate mechanisms either to provide a signal to warn of an intruder or to cause detonation of the device or mechanism. Some of these prior art devices utilize the vibratory or flexing characteristic of a spring and mass combination to effect an electrical switch closure. Other devices use the free rolling motion of a ball to contact a post to affect the closure of an electrical contact and warn of movement to the device. Some mechanical anti-disturbance devices utilize the frictional force between two surfaces to control the release of a carefully balanced lever which is in turn restraining the release of a firing pin being held by a ball detent spring arrangement.

All of the aforementioned devices utilizing a combination of mechanical and electrical means are more difficult to assemble, less reliable over long term periods, because of the dependence upon a relatively short lived battery or some other electrical energy source to activate the device. The prior art frictional release type devices using a balanced lever member to control the release mechanism are generally too sensitive because they will respond to environmental changes rather than to an affirmative act of an intruder.

The present device provides an anti-disturbance device which is insensitive to normal battlefield disturbances such as sonic booms, rain, wind and heat, but is sensitive to movement caused by the device being stepped upon, pushed, kicked, or picked up by an intruder. The present invention is very reliable over long periods of time because of the structural integrity of its parts. Furthermore, the present device is not dependent upon either the activation of an electrical source of power or the life of an electrical power source.

SUMMARY OF THE INVENTION The present invention is an omni-directional antidisturbance device which utilizes the principle that only a small amount of force on the extension of an outer turn of a spirally wound spring can control a larger force being exerted against the inner convolutions of the spiral. In the present invention the inner convolution of the spiral spring are used to restrain a ball detent from releasing a spring loaded firing pin. While the device is in an armed quiescent state the outer turn of the spiral is firmly held against a main body spring locking groove, by a cam located on a rotary pendulous mass. Slight motions caused to the device, after arming, by an intruder will cause the ro-' tary pendulous mass to rotate to a new point,'shifting the attached cam and releasing the spirally wound spring and thereby permitting the force exerted by the spring loaded firing pin to overcome the ball detent.

One of the objects of this invention is to provide an omni-directional anti-disturbance device which is insensitive to normal battlefield conditions such as sonic booms, rain, wind and temperature changes.

Another object of this invention is to provide an antidisturbance device which can be left in position and remain operative over very long periods of time.

Another object of this invention is to insure the operation of an anti-disturbance device which is independent of an electrical power source for its operation.

Another object of this invention is to provide an antidisturbance device having structurally sound parts.

Another object of this invention is to provide an antidisturbance device which is small in physical size and relatively cheap to manufacture.

For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial cross section and elevational view of the anti-disturbance device showing the device in its unarmed or safe condition.

FIG. 2 is a cross-sectional view of the antidisturbance device illustrated in FIG. 1 taken along line 2-2.

FIG. 3 is a cross-sectional view of the antidisturbance device illustrated in FIG. 2, and taken along line 3-3.

FIG. 4 is a partial cross-sectional view of the antidisturbance device illustrated in FIG. 2, and taken along line 4-4.

Throughout the following description like reference numerals are used to denote like parts in the drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, a housing 98 consists of a first circular main body flange 100 and a body shaft 112 integrally attached thereto so that its longitudinal axis 113 is perpendicular to the planar faces of the body flange 100 and concentric therewith. The body shaft 112 has a first firing pin bore 101 and a second spring bore 104. The firing pin 200 is held within the body shaft 112 by a ball detent 111 against the force being exerted against the firing pin spring flange 204 by the spring loaded firing pin spring 202. The tight inner convolutions of spiral spring 300 hold the ball detent 111 in the firing pin groove 201. The inner convolutions of the spiral spring 300 are kept tightly wound by having the helix spring extention 301 to which has been affixed a trip terminal stop 303 wedged intermediate to a spring locking groove 109 and a holding cam 408. A second rotor stop flange 105 of smaller diameter than the body flange 100 helps locate and hold the spiral spring 300 intermediate to the main body flange 100 and adjacent to the ball detent 111. A rotor wheel 400 has the holding cam 408 fixedly attached to its inner surface and is positioned intermediate to the rotor stop flange 105 and a retaining member 108 (shown in FIG. 2). When the device is in the unarmed, safe position, a locking pin 410 and locking pin spring 4! l prevents the rotation of the rotor wheel 400 with respect to the main body flange 100. After the lock pin 410 is removed the device will be in the armed state. When any subsequent substantial tilting motion is given to the device the ball pendulous mass 407- will shift in the rotor wheel rim 402 since the balls only partially fill the wheel rim 402 causing a shift in the rotor wheels 400 center of gravity. This shift in center of gravity will cause the rotor wheel 400 to rotate and permit the partial helical shaped spring extention 301 with its attached trip terminal 303 to jump off the spring locking groove 109 and rapidly unwind so that the inner convolutions of the spiral spring 300 will no longer retain ball detent 111 against the lateral force being exerted against it by the firing pin spring 202. The trip terminal 303 gas a rear trip terminal stop 304 and a front trip terminal stop 305 which help lock the spring extention 301 between the main body flange 100 and the rotor holding cam 408 while the device is in the armed quiescent state. The trip terminal 303 is helped out of the spring locking groove 109 by a preset helical twist given to the helix spring extention 301 prior to the positioning of the trip terminal 303 intermediate to the locking groove 109 and the holding cam 408. A silicone fluid 406 is contained in the motor rim 402 for the purpose of creating a momentary drag between the rotor rim and the pendulous ball mass 407.

When the disturbance device is utilized in an aerial mine, the locking pin 410 does not release the rotor wheel 400 until the device comes to rest on the ground. The pendulous balls 407 in the rotor wheel rim 402 are free to move in any position before ground impact.

When the device comes to rest, the balls 407, responding to gravitational force will move slowly downward in the rotor wheels oily rim 402.and form a pendulum shape.

In operation, after the device has been at rest for a short time delay, and the balls 407 have completely oriented themselves into the pendulum mass, the locking pin 410 is mechanically disengaged from the rotor wheel locking pin bore 409 by a mechanical means not shown on the illustrations. In the armed position, functioning of the firing pin shaft 200 occurs when a low energy impulse acts on the device causing a shifting of its position and motion to the rotor wheel 400. The rotation of the rotor wheel shifts the holding cam 408 and permits the spiral spring 300 to rapidly unwind and expand to a free position. The unwound spiral releases the ball detent 111 from its locked position, permitting the spring loaded firing pin shaft 200 and the firing pin 203 to be accelerated down the firing pin bore 101 toward a detonator 205.

Referring to FIG. 2 the aforementioned body shaft 112 has a first firing pin bore 101 and a second firing pin spring bore 104 of slightly larger diameter and concentric therewith. A spiral spring bore 102 is intermediate to the main body flange 100 and the rotor stop flange 105 and perpendicular to the longitudinal axis 113. The diameter of the spiral spring bore 102 is large enough to hold a portion of the fixed spiral spring end 302. A detent bore 103 slightly larger in diameter than the ball detent 111 and oppositely disposed from the spiral spring bore 102 holds the ball detent 111 so that it contacts the firing pin detent groove 201. The rotor wheel 400 is free to rotate upon the rotor shaft 106 when locking pin 410 is removed from lock pin bore 409. The rotor wheel hub 401 has a centrally located rotor bore 403 which slidably engages the rotor shaft 106. There is a minimum of friction contact between the aforementioned hub and rotor shaft because the rotor wheel 400 is made of a low friction material such as TEFLON while the body shaft 112 is of steel. A cylindrical TEFLON rotor cover 404 is sealed to the peripheral outer edges of the rotor rim 402. The sealed annular cavity formed by the rotor cover 404 and the U-shaped rotor rim 402 provides a sealed track for the ball pendulous mass 407 to ride in and effectively retains the silicone oil 406 which acts as a drag on the ball.

FIG. 3 shows the circular shape of the main body flange 100. A kidney shaped hole 110 in the main body flange is located adjacent to the spring locking groove 109. The kidney shaped hole in this position provides clearance for the rear trip terminal stop 304 when the device is in the unarmed and armed condition so that the trip terminal 303 will properly seat in the spring locking groove 109. The kidney shaped hole 110 in this position also insures non-interference with the rotational unwinding motion of the spring extention 301 when the device is triggered by movement of the rotor wheel 100.

Referring to FIG. 4, the partial cross-sectional view taken along line 4-4 in FIG. 2 shows how the trip terminal 303 nests in the spring locking groove 109 and how the rear trip stop 304 is positioned in back of the locking groove projections 114 and 114'.

From the above description it will be evident that the invention provides an anti-disturbance device which can be safely positioned in an unarmed state, and when armed will not be responsive to normal battlefield disturbances, such as sonic boom, rain, wind, but will be sensitive to movement and omni-directional impulses given to the device by an intruder.

wish it to be understood that I do not desire to be limited to the exact detail of construction shown and described for obvious modifications will occur to a person skilled in the art.

What is claimed is:

1. A mechanical anti-disturbance device for activating a detonator upon the movement of a munition after it has been emplaced which comprises:

a housing means which includes;

a first main body flange having a locking groove located in a peripheral edge;

a body shaft integrally connected and axially aligned with said first flange at one end of said shaft having therein a first central firing pin bore and a second firing pin spring bore of larger diameter concentric therewith for holding said biased firing means, said shaft having a transverse radially positioned spiral spring bore and a transverse radially positioned detent bore;

a second flange, intermediate to said spiral spring and detent bores and said other end of said shaft, for positioning said triggering means on said shaft;

biased firing pin means centrally located within said housing means for initiating a detonator which ineludes;

a firing pin shaft having an annular detent groove proximate one end, a firing pin on the other end, a firing pin spring flange of larger diameter than said firing pin shaft intermediate to said detent groove and said firing pin;

a helical firing pin spring operatively positioned around said firing pin shaft and within said spring bore intermediate to said body shaft and said firing pin spring flange thereby providing said firing pin with energy necessary to activate said detonator when said restraining means releases said firing pin shaft; restraining means operatively positioned on said housing and adjacent to said firing means for holding said firing pin means in a biased position when said device is in an armed condition which includes;

a ball detent slidably positioned in said detent bore so that a portion of said ball detent engages said firing pin shaft detent groove;

a spiral spring having one end held within said spiral spring bore, an inner convolution tightly wrapped around said main body shaft to hold said ball detent against said firing pin shaft detent groove, and the other end having a partial helix configuration;

a trip terminal, carried by said other end of said spring, is held in said main body flange locking groove by said triggering means; and

triggering means rotatably mounted on said housing and coupled to said restraining means for releasing the same when said device is subject to movement which includes;

a rotor wheel having a central hub rotatably supported on said body shaft and including a rotor rim having an annular sealed cavity around the periphery of said wheel, a locking pin bore intermediate said hub and said wheel in an unarmed position when a locking pin is positioned therein during the delivery of the device to the intended area, a cam surface extending from said rotor wheel engaging said trip terminal for releasably holding said trip during the delivery of the device to the intended area, a cam surface extending from said rotor wheel engaging said trip terminal for releasably holding said trip terminal in a locked position;

a plurality of balls slidably held within said annular sealed cavity for providing a pendulous mass sensitive to changes in position of said antidisturbance device;

said annular cavity filled with a silicone oil for providing a drag force between said pendulous mass and said rotor wheel responsive to movement of said anti-disturbance device. 

1. A mechanical anti-disturbance device for activating a detonator upon the movement of a munition after it has been emplaced which comprises: a housing means which includes; a first main body flange having a locking groove located in a peripheral edge; a body shaft integrally connected and axially aligned with said first flange at one end of said shaft having therein a first central firing pin bore and a second firing pin spring bore of larger diameter concentric therewith for holding said biased firing means, said shaft having a transverse radially positioned spiral spring bore and a transverse radially positioned detent bore; a second flange, intermediate to said spiral spring and detent bores and said other end of said shaft, for positioning said triggering means on said shaft; biased firing pin means centrally located within said housing means for initiating a detonator which includes; a firing pin shaft having an annular detent groove proximate one end, a firing pin on the other end, a firing pin spring flange of larger diameter than said firing pin shaft intermediate to said detent groove and said firing pin; a helical firing pin spring operatively positioned around said firing pin shaft and within said spring bore intermediate to said body shaft and said firing pin spring flange thereby providing said firing pin with energy necessary to activate said detonator when said restraining means releases said firing pin shaft; restraining means operatively positioned on said housing and adjacent to said firing means for holding said firing pin means in a biased position when said device is in an armed condition which includes; a ball detent slidably positioned in said detent bore so that a portion of said ball detent engages said firing pin shaft detent groove; a spiral spring having one end held within said spiral spring bore, an inner convolution tightly wrapped around said main body shaft to hold said ball detent against said firing pin shaft detent groove, and the other end having a partial helix configuration; a trip terminal, carried by said other end of said spring, is held in said main body flange locking groove by said triggering means; and triggering means rotatably mounted on said housing and coupled to said restraining means for releasing the same when said device is subject to movement which includes; a rotor wheel having a central hub rotatably supported on said body shaft and including a rotor rim having an annular sealed cavity around the periphery of said wheel, a locking pin bore intermediate said hub and said wheel in an unarmed position when a locking pin is positioned therein during the delivery of the device to the intended area, a cam surface extending from said rotor wheel engaging said trip terminal for releasably holding said trip during the delivery of the device to the intended area, a cam surface extending from said rotor wheel engaging said trip terminal for releasably holding said trip terminal in a locked position; a plurality of balls slidably held within said annular sealed cavity for providing a pendulous mass sensitive to changes in position of said anti-disturbance device; said annular cavity filled with a silicone oil for providing a drag force between said pendulous mass and said rotor wheel responsive to movement of said anti-disturbance device. 